This proposed research is to study the chemical composition of elastin in normal human aging aortas and large arteries. Normality will be determined by histopathologic examination. We plan to isolate chemically intact elastin from these normal vessels and to analyze for its quantity, for its amino acid composition, and also for the number of free NH2-terminal amino acids present as well as their total amounts. Statistical analysis of variance will be used to correlate the data. The purpose of the study is to establish a baseline of aging with respect to these parameters. Collagen associated with each elastin sample will also be measured.